超长PHC管桩桩顶沉降特性的动静对比分析

通过静载荷试验可直接测到桩顶的荷载-沉降（Q-s）曲线。由管桩内预先埋设的应变计的内力测试结果可计算出土阻力与桩-土相对位移的关系，并进一步做高应变测试和拟合分析，得出了高应变拟合的Q-s曲线。对Q-s曲线作动静结果对比分析，探讨了在深厚软土中的超长PHC管桩的桩顶沉降特性。结果表明，当荷载不大时，高应变拟合的沉降大于静载实测的沉降，但当荷载接近极限值时高应变的沉降小于静载的沉降。结果亦表明，当超长PHC管桩桩身穿过一定深度的好土层、桩端进入全风化或更好的岩层时，不管是静载试验还是高应变动力测试，都很难使土阻力得到充分发挥，此时静载实测的和高应变拟合的Q-s曲线都呈缓变型特征。

Dynamic and static comparative analyses of settlements of overlength PHC pipe piles

Based on the test results of prestressed high strength concrete(PHC) pipe piles by static and high strain dynamic load testing, Q-s curves of test piles have been achieved; and the relation between the soil resistance and relative displacement between pile and soil is calculated through the stress test. Comparative analysis of the Q-s curves between the dynamic and static load testing is made; and the settlement behavior of PHC pipe piles is discussed. Results show that the settlement of pile calculated by high strain dynamic load testing is higher than that of pile tested by static load testing when load is smaller; and it is smaller than the result of the static load testing when load gets larger. The results also show that the end bearing of the pile can not exert sufficiently when the pile driven into the full efflorescence granite or the higher intensity of the soil in spite of the dynamic or the static load testing; and the Q-s curves of test piles have the character of slow transmutation.